The present invention relates to a power steering device that assists a steering operation of a vehicle driver by means of a hydraulic.
A Japanese Patent Application First Publication No. 2000-142434 published on May 23, 2000 exemplifies a previously proposed power steering device. In the disclosed power steering device, a drive current flowing through an electric motor is detected, a temperature rise corresponding to a heat generation quantity of a driver element developed due to this drive current per unit time is determined from its data, accumulates the temperature rise in terms of time to derive a temperature rise value with respect to an oil temperature, and the oil temperature is estimated from this temperature rise value and a temperature of the driver element.